Avoid doing a large number of small allocs in readline_helper.

1 files changed, 26 insertions, 7 deletions

diff --git a/dynstr.c b/dynstr.c
index de02f79..a77b2b6 100644
--- a/dynstr.c
+++ b/dynstr.c
@@ -376,9 +376,11 @@ static Dynstr *readline_helper(int (*callback)(FILE *, int), FILE *f, int fd)
     Dynstr *temp1;
     Dynstr *temp2;
     int c;
-    unsigned char byte;
+    unsigned char buf[1024];
+    size_t buflen;
     
     line = dynstr_new_empty();
+    buflen = 0;
 
     for (;;) {
         temp1 = NULL;
@@ -390,19 +392,36 @@ static Dynstr *readline_helper(int (*callback)(FILE *, int), FILE *f, int fd)
         else if (c == -2)
             break;
 
-        byte = c;
-        temp1 = dynstr_new_from_constant_memory(&byte, 1);
+        buf[buflen++] = c;
+        if (buflen == sizeof(buf)) {
+            temp1 = dynstr_new_from_memory(buf, buflen);
+            if (temp1 == NULL)
+                goto error;
+            temp2 = dynstr_cat(line, temp1, NULL);
+            if (temp2 == NULL)
+                goto error;
+            dynstr_free(temp1);
+            dynstr_free(line);
+            line = temp2;
+            buflen = 0;
+        }
+
+        if (c == '\n')
+            break;
+    }
+    
+    if (buflen > 0) {
+        temp1 = dynstr_new_from_memory(buf, buflen);
         if (temp1 == NULL)
             goto error;
         temp2 = dynstr_cat(line, temp1, NULL);
+        if (temp2 == NULL)
+            goto error;
         dynstr_free(temp1);
         dynstr_free(line);
         line = temp2;
-
-        if (c == '\n')
-            break;
     }
-    
+
     return line;
 
 error: